Last night was Fireworks Night at Shea Stadium. Therefore, it might have been wise to fit Armando Benitez with a flame-retardant uniform, or perhaps to wrap him in a fireproof blanket, to make sure the explosives weren’t prematurely set off all at once.

A walking supernova with a stick of dynamite for a right arm, Benitez blew his sixth save of this lost Mets season Tuesday night against the Expos, yet got credit for the win in a 7-6 victory.

Benitez came on in relief of Graeme Lloyd in the eighth inning and allowed Jose Vidro to tie the game, 6-6, with a two-out, full-count, two-run homer that left the park quicker than the closer might be traded.

“I thought he made one bad pitch,” Art Howe said. “It’s too bad it went out of the ballpark.”

“It’s my fault,” Benitez said.

Earlier that afternoon, Robbie Alomar was traded in a move that sent shivers through the Mets clubhouse, where players questioned who would be next out of town, with a purge of their last-place locker room clearly under way.

Benitez, in the final year of a contract that pays him $6.937 million this season, is the next likely candidate to be shipped off for prospects, as Alomar was to the White Sox.

With Benitez’s stock sinking like a stone with each blown save (he has six in 25 opportunities), how realistic is it to trade him for anyone?

“One mistake,” Benitez said of his latest blown save. “I take responsibility. I threw the pitch. But if I struck him out, everybody would be happy.”

His six blown saves this year already ties a career high, matching the six he had during the entire 1999 season. They also tie Benitez for the major league lead in that dubious category; his 19 saves in 25 chances rank him sixth in the National League.

In the last week, however, the man who converted 117 of 129 (90.7 percent) save opportunities the last three years (a major league best, ahead of Trevor Hoffman’s 90.5 percent) has been as inconsistent as he’s ever been in his 10-year career.

“I think what I have to do is throw my best pitch,” Benitez said of his 97-mph fastball.

Benitez seems to still be reeling from the blown save he had June 22 against the Yankees, in which he walked four batters, blowing a 3-2 lead in a game the Mets lost 7-3 in 11 innings.

In his career, Benitez has 33 blown chances, and it’s never been more clear that he’s out of chances with his current employers, as well as with the fans at Shea who boo him without mercy.

“I don’t think about that,” Benitez said.

“Just ignore them,” Howe said of the fans. “Nothing has changed.”

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Night & day

Mets closer Armando Benitez has fared much better at night – and away from Shea Stadium – this season.